The present invention relates generally to systems and methods for lubricating movable machine parts, and more particularly to a novel sublimation system and method for providing high temperature, low friction lubrication to bearing surfaces.
Operation of bearings, gears, cams and other mechanical components in conventional gas turbine and automotive engines are generally limited to temperatures of about 350-400.degree. F. because the conventional liquid lubricants used in the engines usually thermally decompose above about 400.degree. F. Advanced turbine engines and other high temperature engine types (stirling, adiabatic, diesel) may require bearing operation above 1000.degree. F. and therefore require alternate lubrication systems. Conventional solid lubricants such as molybdenum disulfide (MoS.sub.2) and tungsten disulfide (WS.sub.2) are useful to about 800.degree. F. and may be used in coating or powder form. Advanced solid lubricants such as cesium oxythiotungstenate (Cs.sub.2 WOS.sub.3) and other complex chalcogenide lubricants, either in coating or in powder form, have been shown to perform well at temperatures above 1200.degree. F. However, specialized equipment for pretreating bearing surfaces and applying a lubricant coating thereon, or for delivering the powder form to the bearing surfaces, in the utilization of advanced lubricants in either coating or powder form may be required.
The invention solves or substantially reduces in critical importance problems with existing lubricant systems by providing system and method for supplying lubricant to high temperature operating bearing surfaces by heating a selected solid lubricant to vapor form and conducting the lubricant vapor, by sublimation, to the bearing surface to be lubricated.
The invention provides numerous advantages over previously known lubrication techniques for high temperature engine applications, including improved engine performance through higher operating temperature capability, and the elimination of any need for coating processes, powder delivery systems, large lubricant reservoirs or lubricant scavenge and supply pumps.
It is therefore a principal object of the invention to provide improved system and method for lubricating bearing surfaces of moving machine parts.
It is another object of the invention to provide system and method for high temperature lubrication of machine parts.
It is a further object of the invention to provide system and method for high temperature lubrication of machine parts using lubricant sublimation.
These and other objects of the invention will become apparent as a detailed description of representative embodiments of the invention proceeds.